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Irrigation system can grow crops with salt water

A British company has created an irrigation system that can grow crops using salt water.

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The dRHS irrigation system consists of a network of sub-surface pipes, which can be filled with almost any water, whether pure, brackish, salted or polluted. The system can even take most industrial waste-water and use it without the need for a purification process.

The pipes are made from a plastic that retains virtually all contaminants while letting clean water through to the plants' roots.

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It was designed by Mark Tonkin of Design Technology and Irrigation, which is based in Brighton. He says that once the pipes have been laid, the system will require little maintenance and therefore no significant costs. This is partly because it's fed by gravity from an elevated supply tank, and partly because water diffuses through the porous pipe walls, so there are no holes to get blocked up.

The farmer will occasionally have to flush the pipes to clean out salt crystals and dirt, but Tonkin says this is a simple process.

Since the water is delivered directly to the plant roots, there is much less wastage through evaporation and run-off than with traditional irrigation systems. According to the inventor, it is also impossible to over-water plants, as the system will only release more water as plants draw up clean water from the soil.

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The dRHS system, which has been in development for ten years, was initially trialled in the UK using tomato plants, and has since been tried out in the US. The next trials will take place in Chile, Libya, Tanzania, Mauritius and Spain. Tonkin says 20,000 metres of pipe are on their way to the Middle East, where it will be tested with water that's more saline than sea water.

The system has so far supported the growth of tomatoes, radishes, courgettes, peppers, lettuce, strawberries and beans as well as three different types of tree - cherry, olive and prosopis. The company is now trying to grow acacias, oaks and banana trees among others.

Christopher Gasson from Global Water Intelligence magazine says that the competition was a three-way tie last year but this year, the winner stood out. "The dRHS irrigation system addressed a bigger problem than the other technology that it was competing against," he said. "Agriculture water is where 70 per cent of water goes. By 2025 two thirds of the world’s population will experience water shortages and so farming will be badly hit. "Salination is a huge problem. Already 97.5 per cent of the water in the world is salty, and this is becoming more of a problem as people in poor countries recycle water, sometimes leaving the soil with a salty crust. This system will help a lot."